Does atmospheric combustion Fe enhance primary production in the surface ocean? An investigation from Fe isotope ratios

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K23369
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 1101:Environmental analyses and evaluation, environmental conservation measure and related fields
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: Kurisu Minako 国立研究開発法人海洋研究開発機構, 海洋機能利用部門(海底資源センター), 研究員 (80880864)
• Project Period (FY): 2020-09-11 – 2023-03-31
• Keywords: 鉄安定同位体 / 植物プランクトン / エアロゾル / 人為起源

Outline of Final Research Achievements

Iron (Fe) deficiency is one of the limiting factors of the phytoplankton productivity in the ocean. The objective of this study was to quantitatively evaluate whether phytoplankton can utilize Fe in aerosols emitted by anthropogenic activities, and the associated changes in iron stable isotope ratios. We conducted laboratory culture experiments with diatoms. Different sources of aerosols (natural dust and anthropogenic aerosol) was added to seawater culture containing diatoms, and quantified the degree of diatom growth and changes in stable isotope ratios.
The results confirmed that both natural and anthropogenic particles caused diatom growth and were available to the organisms. Regardless of the origin of Fe, diatoms exhibited higher isotope ratios to the seawater, suggesting that diatoms selectively take up heavier isotopes.

Free Research Field

地球化学

Academic Significance and Societal Importance of the Research Achievements

海洋における鉄の不足は、植物プランクトンの増殖を制限することで、海洋の炭素循環に大きな影響を及ぼし、ひいては大気中の二酸化炭素濃度などの変動を介して、気候変動にも関わる。そのため、鉄がどこからどのように供給されて、生物の増殖に寄与しているかを知ることが海洋化学の目標の一つとなっている。本研究で得られた、鉄の取り込み機構の定量的な情報は、今後天然環境における鉄の取り込み機構を包括的に理解し、例えば数値モデルなどを用いて全球的な鉄循環・炭素循環の推定をする上で重要となる。